Most plug-ins work. I've sucessfully tried Magic Bullet, Sapphire, HFX, Procoder, Immaginate, Trapcode, Spicemaster v2.5 and Adorage. Heroglyph v2 is posing problems (probably transparency)and thats all from the demo. Didn't reload anything, simply moved the plugins from PP1.5 to PP2.0. I'll try more later. Oh! And Smartsound works as well.
Canopus ProCoder does not work. SmartSound QuickTracks has an issue with audio waveform drawing for long clips that can be worked around: http://www.smartsound.com/support/answers/link.php?id=493. Automatic Duck Pro Import PPro, Pro Export PPro, 2d3 SteadyMove, Synthetic Aperture Color Finesse, Red Giant Movie Looks, and StageTools MovingPicture will require an update for 2.0. And of course United Media Multicam is no longer needed with the new multicam functionality built-in. Most other plug-ins work quite well.
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